Significance of the duration of nephropathy for achieving clinical remission in patients with IgA nephropathy treated by tonsillectomy and steroid pulse therapy.

BACKGROUND: Because of the well-established annual urinalysis screening system in Japan, the duration of nephropathy (DN) can be estimated in more than half of all patients with IgA nephropathy (IgAN). Treatment using a combination of tonsillectomy and steroid pulse (TSP) therapy has been reported as an effective method for obtaining clinical remission (CR), defined as negative hematuria and proteinuria, in IgAN patients. The present study aims to identify the correlation between DN and CR rate in IgAN patients treated by TSP therapy. METHODS: We retrospectively investigated 830 IgAN patients who were followed up for 81.6 months after TSP therapy. DN could be estimated in 495 of the 830 patients. RESULTS: The CR rate among patients with DN ≤36 months was 87.3% (295/338 patients). The CR rate among patients with DN of 37-84 months was 73.3% (63/86 patients), while that among patients with DN ≥85 months was 42.3% (30/71 patients). The CR rate among the remaining 335 patients in whom DN could not be estimated because of missing annual urinalysis results was 43.6% (146/335 patients). A multivariate Cox regression model using data from the former group of 495 patients showed that DN ≤36 months was a significant predictor of CR (hazard ratio 1.839; 95% confidence interval 1.410-2.398; P < 0.001). CONCLUSION: Shorter DN is associated with higher likelihood of clinical remission in IgAN patients treated by TSP therapy.